Crescent shaped reed valve



firzr-fh Nov. 11, 1958 R. H. swART ET AL 2,859,912

CRESCENT SHAPED REED VALVE Filed April 25. 1953 IiE- 1 VIII/1111111 I-INVENTOR.

United States 'PatentO CRESCENT SHAPED REED VALVE Richard H. Swart,Syracuse, and Robert W. Ayling, Utica, N. Y., assignors to CarrierCorporation, Syracuse, N. Y., a corporation of Delaware ApplicationApril 23, 1953, Serial No. 350,571

6 Claims. (Cl. 230172) This invention relates to compressors and, moreparticularly, to reciprocating hermetic compressors employed inrefrigerating systems having a cylinder head whose discharge gas volumeis substantially increased Without substantially changing the height ofthe head.

The efiiciency of a reciprocating compressor depends to some extent onthe head pressure. In reciprocating compressors, at the start of thesuction stroke, there remains in the piston cylinder a small volume ofthe compressed fluid. from the prior compression stroke. This leftoverfluid is due to the fact that there must be a slight clearance betweenthe top of the piston at the end of its stroke and the valve plate.

The ratio of the volume of this left-over fluid to the volume ofincoming suction fluid will depend on the ratio of the pressure in thehead, which is, the pressure of the left-over fluid, to the suctionpressure. Thus, the higher the head pressure in comparison to thesuction pressure, the greater volume the left-over fluid occupies atsuction pressure. It is, of course, desirable to keep the volume of theleft-over fluid at suction pressure as low as possible since it is notdesired to recompress any more fluid than necessary.

If the head pressure can be reduced, then the efliciency of thecompressor will be increased. Since the compressor will be operatingmore efliciently, it willhave a greater capacity with the same amount.of power consumption.

The head pressure is reduced if the volume of the discharge chamber inthe head is increased since this will permit the compressed gas toexpand more rapidly and therefore have a lower pressure, which is closerto the condenser pressure.

However, in hermetic type compressors, the casing limits the height ofthe head so that it is not possible to increase the height of the headto increase the volume of the discharge chamber without increasing theover-all size of the compressor, and this is not desirable. Ourinvention permits an increase in head volume without increasing theheight of the head to provide a more eflicient compressor with the samesize casing and compressor. Q

We have satisfactorily solved this problem by tremendously increasingthe head volume for the discharge gas.

By disposing the discharge ports on an arc of a circle, we have beenable to dispose the discharge chamber over a greater portion of the headthanpreviously. T his increase in head volume for the discharge gasresults in the pressure of the head gas being closer to the condenserpressure and the volume of left-over fluid in the cylinder at the end ofthe suction stroke being decreased.

It also will be noted that the increase in the discharge gas chamber inthe head results in a quieter compressor. This is due to the fact thatthe compressed fluid has more volume into which to expand. Since thedischarge gas enters the head approximately thirty times a second, itwill be understood that a decrease in this noise will be a large factorinquieter operation of the compressor.

2,859,912 Patented Nov. 11, 1958 ICC The chief object of this inventionis to provide a compressor having an increased capacity withoutincreasing the size of the compressor.

An object of the invention is to provide a cylinder head of a compressorwith an increased volume for discharge gas without substantiallyincreasing the thickness of the head.

Another object of this invention is to provide a compressor thatoperates more efficiently than present compressors.

A further object is to provide a compressor valve reed of novel design.Other objects of our invention will be readily perceived from thefollowing description.

This invention relates to a reciprocating compressor including, incombination, a compression cylinder, a cylinder head disposed above thecylinder, a valve plate disposed between the cylinder and the head, saidvalve plate including suction and discharge ports to providecommunication between the head and the'cylinder, said head cooperatingwith said valve plate to form'two chambers in the head, one of saidchambers being above the suction ports, the other of said chambers beingabove the discharge ports, said second chamber being of a greater volumethan said first chamber, a valve r'eed disposed above the ports, meansdisposed above the reed in the second chamber to permit the reed to liftto permit gases to flow through the discharge ports when the gaspressure in the cylinder reaches a predetermined amount, and means tocover the suction ports to permit gas to enter the cylinder and toprevent discharge gases from entering the first chamber.

discharge ports therein, said discharge ports being disposed about thearc of a circle, a crescent shaped valve reed adapted to close thedischarge ports, means to permit the reed to lift when the pressure inthe cylinderreaches a predetermined amount, and means to prevent flow ofdischarge gas through the suction ports.

The attached drawings-'illustratea preferred embodiment of ourinvention, in which v p Figure 1 is a sectional view'of the compressioncylinder of the present invention; 7 I

Figure 2 is a planview of the valve plate taken from the head side;

Figure 3 is a plan view of the valve plate taken from the compressioncylinder side; i 1

Figure 4 is a plan view of the discharge valve reed;

Figure 5 is a-plan view of the suction valve reed;

Figure 6 is a bottom plan view of the cylinder head of the presentinvention; and

Figure 7 is a fragmentary view in section illustrating a crescent-shapedsuction valve reed disposed on the valve plate.

Referring to the drawings, and particularly to Figure 1, there is showna compression cylinder 2 within which a piston, not shown, is mountedfor reciprocatory movement in the well-known manner and above which isdisarc of a circle as clearly shown in Figure 2.

rate the cylinder head 3 from the cylinder 2. V This valve platepreferably has a. plurality of discharge ports 5 therein. Thesedischarge ports are arranged along the It will be understood that asingle slot or opening forming the arc of a circle could be used, ifdesired. The valve plate also has suction ports 6 therein. Flow of gasthrough the discharge ports 5 is regulated by a crescent shaped valvereed 7, shown in Figure 4. A suction valve reed 8, shown in Figure 5,regulates the flow of gas through the suction ports 6. Note that thesuction valve reed has an opening 9 therein. This opening permitsmounting of the suction valve reed without blocking the discharge ports.It will be understood, as shown in Figure 7, that the suction ports 6could be arranged on the arc of a circle in the same manner as thedischarge ports and the suction valve med 8 could be crescent shapedsimilar to discharge v lye reed 7.

Referring to Figures 1' and 6', the head}; has a su ction chamber 12 anda, discharge chamberlfl separated byan arcuate partition 14. The suctionchamber is disposed above the suction ports, while the discharge chamber'is disposed above the discharge ports. The discharge cham ber 14 is ofa larger volume than the suction chamber 12.

'As clearly shown in Figures 1 and 6, the discharge chamber 14 extendsbeyond the center of the head'. The discharge chamber extends nearly thecomplete diameter of the head and is shaped to be disposed over thedischarge ports 5 in the-valve plate 4. While the discharge chamber isnarrow width at its ends,'note Figure 6, it increases substantially andquickly in width in the center portion.

The suction chamber 12 is disposed on one side of the center of thehead. This chamber extends across only a portion of the head. Itsgreatest depth is adjacent the discharge chamber while it is shallow indepth at the points nearest theouter edge of the head.

Suction gas flows by suitable means into the suction chamber 12 and thenthrough the suction ports 6 and past the suction valve reed 8 into thecompression cylinder 2. Discharge gas flows frorn'the cylinder 2 intothe discharge ports 5 and past the discharge valve reed 7 to the discharge chamber 14 of the head 3. From the head, the gas flows to thecondenser, not shown.

' Means must be provided to insure that the suction gas does not flowinto the discharge chamber or vice versa. A gasket is disposed betweenthe valve plate 4 and the cylinder head 3 to seal the suction chamberfrom the discharge chamber. This gasket is preferably made of a mixtureof polymerized polychloroprene and asbestos fibers but other suitablesimilar materials may be employed, if desired. To insure thatthe gasketperforms its function satisfactorily, a groove may be provided in thespace between thechambers 12 and 14 on the valve plate 4. If desired,instead of a groove, a crown may be provided on the valve plate. While agroove or crown may be used, it is not necessary that such means beemployed to insure the sealing. A gasket 15, preferably made of the samematerial as the gasket 15, is disposed between the valve plate 4 and thetop of cylinder 2 to prevent leakage.

The valve reed must be prevented from uncovering the discharge portsuntil the gas has been compressed in the cylinder 2. To prevent the reedfrom lifting until the desiredtime, a crescent shaped stop 16 isdisposed above the reed. A spring 17 is disposed between the stop 16 andthe head 3 to apply the desired force to the stop 16 to prevent the reedfrom lifting until a desired pressure exists in the cylinder 2. Whilethe reed and the stop are crescent shaped, it is preferred to make thespring straight. Of'course, if desired, the spring may be crescentshaped.

By making the reed crescent shaped, the distance between the ends of thereed along. a centerline is greater than, th distance along thecenterline of a straight 'valye reed, and this permits the reed touncover the ports with less strain. This construction also permits thereed to lift obliquely when it uncovers the ports. This results in arelatively low resonant reed frequency thereby causing the opening andclosing action to be less noisy; The greater length of thereed along itscenterline has the advantage of permitting more discharge ports to bedisposed beneath it. The tendency of the discharge gas to enter the headrapidly is reduced by the present invention; thus, the performance ofthe compressor is improved,

A further advantage ofthe present inventionis to prov de a compressorwith an increased number of discharge ports to lower 'the gas velocitypassing therethrough.

Still another advantage of the invention is the provision of acompressor valve plate with discharge ports disposed on the arc of acircle.

While we have described a preferred embodiment of our invention, it willbe understood that our invention is not limited thereto since it maybeotherwise embodied within the scope of the following claims.

We claim:

'1: In a reciprocating compressor including a compressor cylinder; apiston mounted within the cylinder for reciprocating movement therein; acylinder head, including a suction chamber anda discharge chamberdisposed above the cylinder; a valve plate interposed between said headand cylinder, said plate including a plurality of arcuately disposeddischarge passages permitting communication between the dischargechamber in the head and the cylinder, and a plurality of suctionpassages permitting communication between the suctionchamber in the headand the cylinder; a valve comprising substantially a crescentshaped reedoverlying said discharge passages, said reed being secured at itsextremities to the upper surface of the valve plate; and'means securedtothe underside of the valve plate adapted to permit flow of gas into thecylinder as the piston is retracted from the valve plate and to preventthe flow of gas into the cylinder when the piston is moved toward thevalve plate, said last mentioned means including a secondcrescent-shaped reed.

2. In a reciprocatingcompressor including a compressor cylinder; apiston mounted within the cylinder for reciprocating movement therein; acylinder head, including a suction chamber and a discharge chamberdisposed adjacent the cylinder; a valve, plate interposed between saidhead and cylinder, said plate including a series of arcuately disposeddischarge passages permitting communication between the dischargechamber in the head and the cylinder, and at least one suction passagepermitting communication between the suction chamber in the head and thecylinder; a valve comprising substantially a crescent-shaped reedoverlying said discharge passages, said reed being secured at itsextremities to the upper surfaceof the valve plate, means positionedabove the reed in the discharge chamber of the head for preventingmovement of the reed in the absence of a predetermined pressure withinthe cylinder; and means secured to the underside of the valve plateadapted to permit flow of gas into the cylinder as the piston isretracted from the valve plate and to prevent the flow of gas into thecylinder when the piston is moved toward the valve plate.

3. In a reciprocating compressor including a compressor cylinder; apiston mounted within'the cylinder for reciprocating movement therein; acylinder head including a suction chamber and a discharge chamber; avalve plate interposed between said head and cylinder, said plateincluding a series of arcuately disposed discharge passages permittingcommunication between the discharge chamber in the head and thecylinder, and at least one, suction passage permitting communicationbetween the suction chamber in the head and the cylinder; a valvecomprising substantially a crescent-shaped reed overlying said dischargepassages, said recd being secured proximate its extremities to thesurface of the valve plate which forms a part of the discharge chamber;and means secured to the other side of the valve plate adapted to permitflow of gas into the cylinder from the suction chamber as the piston isretracted from the valve plate and to prevent the flow of gas from thecylinder into the suction chamber when the piston is moved toward thevalve plate.

4. A reciprocating compressor as set forth in claim 3 wherein saiddischarge chamber is generally of substantially crescent-shapedconfigurationto provide a maximum volume discharge chamber in a cylinderhead having a limited height.

5. In a reciprocating compressor including a compresso; cylinder;- apiston mounted within the cylinder for reciprocating movement therein; acylinder head, including a suction chamber and a discharge chamberdisposed adjacent the cylinder, said cylinder head being provided with apartition separating the suction chamber from the discharge chamber, atleast a portion of said partition being arcuate; a valve plateinterposed between said head and cylinder, said plate including at leastone discharge passage permitting communication between the dischargechamber in the head and the cylinder, and at least one suction passagepermitting communication between the suction chamber in the head and thecylinder; a valve comprising substantially a crescent-shaped reedoverlying said discharge passage, said reed being secured at itsextremities to the upper surface of the valve plate; and means securedto the other side of the valve plate adapted to permit flow of gas intothe cylinder as the piston is retracted from the valve plate and toprevent the flow of gas into the cylinder when the piston is movedtoward the valve plate.

6. In a reciprocating compressor including a compressor cylinder; apiston mounted within the cylinder for reciprocating movement therein; acylinder head including a suction chamber and a discharge chamber; avalve plate interposed between said head and cylinder, said plateincluding means formed therein having a configuration serving tocooperate with a crescent-shaped reed permitting communication betweenthe discharge chamber in the head and the cylinder, and at least onesuction passage permitting communication between the suction chamber inthe head and the cylinder; a valve comprising substantially acrescent-shaped reed overlying said means, said reed being securedproximate its extremities to the surface of the valve plate which forms.a part of the discharge chamber; and means secured to the other side ofthe valve plate adapted to permit flow of gas into the cylinder from thesuction chamber as the piston is retracted from the valve plate and toprevent the flow of gas from the cylinder into the suction chamber whenthe piston is moved toward the valve plate.

References Cited in the file of this patent UNITED STATES PATENTS986,122 Astrom Mar. 7, 1911 1,273,698 Wainwright July 23, 1918 1,633,772Clapp June 28, 1927 2,001,885 Ohmart May 21, 1935 2,005,959 Smith June25, 1935 2,195,292 Albertson Mar. 26, 1940 2,565,950 Crider Aug. 28,1951

